A formal idiom studied by Charles Fillmore, Paul Kay and Catherine O’Connor in support of their theory of construction grammar (1).

The let alone construction can be described in terms of its syntactic, semantic and pragmatic properties, some of which are regular and some of which are idiosyncratic.

The let alone construction displays regular syntactic properties and is characterized by the presence of the coordinating conjunction let alone, which coordinates two prosodically prominent (stressed) expressions. This construction is illustrated by the sentence in (1) below. In this example, the expressions basic arithmetic and advanced algebra (labeled as A and B respectively) are prosodically prominent, and are coordinated by let alone.

1. John doesn’t understand basic arithmetic let alone advanced algebra A B In semantic terms, the construction has the idiosyncratic property that the coordinated expressions are interpreted as contrasted points on a scale, where the second conjunct (advanced algebra) has greater emphatic force than the first (basic arithmetic). In the context of asking about John’s grasp of advanced algebra, as a result of the let alone construction, the utterance in (1) conveys the information that because John doesn’t understand basic arithmetic, he is even less likely to comprehend advanced algebra. This rests upon the assumption that understanding basic arithmetic is a prerequisite for understanding advanced algebra.

Not only does the construction reject a particular proposition (for example, that John understands advanced algebra), but it does so by providing additional relevant information. The relevant information relates to the first conjunct (A), and establishes an implicational scale between the expressions conjoined by let alone. If John doesn’t understand (A) this implies that he doesn’t understand (B). The pragmatic impact of this construction is that by first rejecting a weaker proposition, the proposition that our attention is focused upon (e.g. whether John understands advanced algebra) is more forcefully negated than it would otherwise have been.